676 



the glands in question are composed of numerous lobules, more or less 

 loosely connected together, and opening by a number of ductules into 

 a common duct. 



By the majority of those, who have occupied themselves with the 

 anatomy of the Oligochaeta^ these glands have in every case been 

 termed »prostates«. 



The questions which are attempted to be answered in the present 

 note are (1) Do these various structures correspond to each other? 

 (2) Are they homologous with any organs found among the lower Oli- 

 gochaeta'ì 



Vejdovsky has expressed the opinion ^ that the tubular gland of 

 Poniodrilus and oï Eudrilus is the atrium of the lower Oligochaeta ; with 

 some little hesitation he suggests that the »prostate« of PericJiaeta may 

 be the equivalent of the prostates (Cement-Driisen) of the Tubifici- 

 dae etc. , and therefore by implication not homologous with the gland of 

 Acanthodrilus. With the former suggestion I fully agree, but I believe 

 that the »prostate« of PericJiaeta is the homologue of that of Acantlio- 

 drilus. 



In Eudrilus there are a pair of »prostate« glands which I have 

 recently shown to have a minute structure identical with that of Acan- 

 thodrilus ^ and, I may add, of Trigaster, Pontodrilus and Typhocus, as 

 regards the epithelial lining; this ressemblance is masked by a great 

 development of muscular fibres giving to these organs their peculiar 

 nacreous appearance. In a less degree the same development of muscles 

 has been found by Benham upon the »prostates« of Trigaster. In 

 Eudrilus'^ therefore there are a pair of organs which seem 

 to be homologous with the »prostates« of ^ca?^^Ä0(/r^7^^s etc. 

 but the vasa deferentia open into them at about their middle. 

 They are in fact not diverticula of the vas deferens, but for the greater 

 part represent merely a dilatation of the vas deferens on its way to the 

 exterior. 



In Eudrilus the terminal part of the male efferent apparatus is 

 highly specialised ; the vasa deferentia enter the glandular body already 

 referred to, and become continuous with its lumen. The glandular 

 body is divided by a longitudinal septum into two halves ^ which are 

 identical in structure and enclosed in a common muscular sheath ; they 

 on their part terminate in two muscular tubes which unite to form a 

 projecting penis lodged in a secondary invagination of the integument 



1 System und Morph, der Oligochaeten. 



2 ContributioDvS to the Anatomy of Earthworms. No. I. Proc. Zool. Soc. 1887. 

 p. 383. 



3 Proc. Zool. Soc. 1. c. 



